PMID: 28471355
Authors:
Wang R, Wu J, Jin DK, Chen Y, Lv Z, Chen Q, Miao Q, Huo X, Wang F
Title:
Structure of NADP+-bound 7beta-hydroxysteroid dehydrogenase reveals two cofactor-binding modes.
Journal:
Acta Crystallogr F Struct Biol Commun. 2017 May 1;73(Pt 5):246-252. doi:, 10.1107/S2053230X17004460. Epub 2017 Apr 26.
Abstract:
In mammals, bile acids/salts and their glycine and taurine conjugates are effectively recycled through enterohepatic circulation. 7beta-Hydroxysteroid dehydrogenases (7beta-HSDHs; EC 1.1.1.201), including that from the intestinal microbe Collinsella aerofaciens, catalyse the NADPH-dependent reversible oxidation of secondary bile-acid products to avoid potential toxicity. Here, the first structure of NADP+ bound to dimeric 7beta-HSDH is presented. In one active site, NADP+ adopts a conventional binding mode similar to that displayed in related enzyme structures. However, in the other active site a unique binding mode is observed in which the orientation of the nicotinamide is different. Since 7beta-HSDH has become an attractive target owing to the wide and important pharmaceutical use of its product ursodeoxycholic acid, this work provides a more detailed template to support rational protein engineering to improve the enzymatic activities of this useful biocatalyst, further improving the yield of ursodeoxycholic acid and its other applications.